Lamenting in English and Gaelic in translation (7)
I believe the answer is:
elegiac
'lamenting' is the definition.
(I've seen this before)
'english and gaelic in translation' is the wordplay.
'english' becomes 'E' (abbreviation).
'and' means one lot of letters go next to another.
'in translation' indicates an anagram (translate can mean to transform).
'gaelic' with letters rearranged gives 'legiac'.
'e'+'legiac'='ELEGIAC'
'in' is the link.
(Other definitions for elegiac that I've seen before include "Mournful as in Gray's poem" , "Wistfully mournful" , "Poetic, mournful" , "Expressing poetic sorrow for something past" , "of valedictory works" .)